In the past, when I’ve been talking to people who care for people with dementia or museum staff who work with people with dementia, I’ve heard statements like:
“[Edith] hardly ever speaks but when we put this CD on she began to sing along with the music. Once the music stopped she returned to being silent.”
or
“[Frank] struggles to walk from one side of the room to the other but when the music played he got up and danced.”
Often these statements are expressed with a sense of wonder and not a little bewilderment.

My assumption is that the explanation (or at least the beginnings of an explanation) can probably be found in the literature. So, as a starting point for inquiring into these phenomena, I thought I would go back and re-read Oliver Sack’s book, ‘Musicophilia’. I was not disappointed. The book is great in that, Sacks never loses sight of the humanity and personhood of his patients and yet he relates their experience to the cognitive processing of / response to music in accessible ways.

As I suspected the human response to music is a complex, multi-faceted thing and as such involves many parts of our brains. For instance, “[Peretz and colleagues] feel that there are two basic categories of musical perception; one involving the recognition of melodies, the other the perception of rhythm or time intervals. Impairments of melody usually go with right-hemisphere lesions, but representation of rhythm is much more widespread and robust and involves not only the left hemisphere, but many subcortical systems in the basal ganglia, the cerebellum and other areas.” (p117)

The bit at the end the quote about the importance is of subcortical systems is significant. To risk a generalisation, many forms of dementia, notably Alzheimer’s Disease and fronto-temporal dementia, are cortical diseases. That is, the sub-cortical systems may be less effected by a dementia. There needs to be some caution here. It is better to think of cognitive systems or circuits being invoked to deal with certain tasks and if part of a circuit breaks down then (notwithstanding any neural plasticity / cognitive reserve effects) the circuit as a whole will be impaired. See, for example Meulenbroek’s thesis.

Bearing that in mind, Chapter. 15 (p201-231) provides some very important insights. Sacks writes about musical performance as procedural memory (or ‘fixed action patterns). “The basis of procedural or implicit memory is less easy to define, but it certainly involves larger and more primitive parts of the brain – subcortical structures like the basal ganglia and cerebellum and their connections to each other and to the cerebral cortex. The size and variety of these systems guarantees the robustness of procedural memory and the fact that, unlike episodic memory, procedural memory can remain intact even in the face of extensive damage to the hippocampi and medial temporal lobe structures.” (p222)

Later in the same chapter, Sacks writes about the “momentum of the music”. Here he is talking about how the rules and structure of music can carry people who are familiar with these through a piece of music – I wonder whether this relates to my feeling that music overcomes barriers to the initiation of action? If so, it would help understand ‘Frank’ and his ability to dance but not get up and walk.

Sacks deals explicitly with music and dementia in Chapter 29 (p371 – p385).
“[The] response to music is preserved even when dementia is very advanced.” (then) Music therapy with patients with advanced dementia “is possible because musical perception, musical sensibility, musical emotion, and musical memory can survive long after other forms of memory have disappeared.” (p372)

There may be limits (p378-379). “There was not, and perhaps could never be, any carryover from performance and procedural to explicit memory and usable memory [for Greg & Woody who had suffered profound amnesia]. While, at least in someone as amnesic as Greg or Woody, singing cannot be used as a sort of back door to explicit memory, still the act of singing is important in itself….” To an extent, the importance of singing for someone depends on the place of music in each person’s earlier life. For Greg and Woody music was huge and therefore continues to carry enormous therapeutic value.

Despite this caution about the limits of music, Sacks goes on… (p379 – p380) “Most patients are not especially gifted in this regard and yet […] they retain their musical powers and tastes even when most other mental powers have been severely compromised. They can recognize music and respond to it even when little else can get through.” Sacks goes on to write about the (potentially) communal and physical response to music. Then: “Familiar music acts as a sort of Proustian mnemonic, eliciting emotions and associations that had been long forgotten, giving patients once again access to moods and memories, thoughts and worlds that had seemingly been completely lost.” (Interestingly his quote from a music therapist brings out the secondary effect that these sessions have on the way that nurses think about their charges.) “Music therapy for patients with dementia traditionally takes the form of providing old songs, which […] call on personal memories, evoke personal responses and invite participation. Such memories and responses may become less available as dementia becomes more profound. Yet some sorts of memory and response almost always survive – above all, the sort of motor memory and motor response that goes with dancing.” […] ‘The body is a unity of actions,’ Luria wrote, and if there is no unity, nothing active or interactive going on, our very sense of being embodied may be undermined.”(p382)

The bit I was looking for came in p385… “The perception of music and the emotions it can stir is not solely dependent on memory and music does not have to be familiar to exert its emotional power. […] [The responses of people with advanced dementia shows that] “there is still a self to be called upon even if music and only music can do the calling. There are undoubtedly particular areas of the cortex subserving musical intelligence and sensibility and there can be forms of amusia with damage to these. But the emotional response to music, it would seem, is widespread and probably not only cortical but subcortical, so that even [in the wake of] a diffuse cortical disease like Alzheimer’s music can still be perceived, enjoyed and responded to. […] Music is part of being human and there is no human culture in which it is not highly developed and esteemed. […] [To] those who are lost in dementia, the situation is different. Music is no luxury to them, but a necessity, and can have a power beyond anything else to restore them to themselves, and to others, at least for a while.”

However, it is not all about memory loss. Chapter 27 (p339 – 352) deals with cases that resemble the behavioural variant of fronto-temporal dementia. The chapter opens up with individuals who, because of their medical conditions, become disinhibited and begin to sing… incessantly. On p348ff Sacks explores the idea that “there is a balance in each individual, an equilibrium between excitatory and inhibitory forces. But if there is damage to the (more recently evolved) anterior temporal lobe of the dominant hemisphere, then this equilibrium may be upset, and there may be a disinhibition or release of the perceptual powers associated with the posterior parietal and temporal areas of the non-dominant hemisphere.” This may lead to a release of creative, musical or artistic abilities.

One idea that I was interested in is the relationship between singing and the act of speaking with the intention to communicate. p342 – 348 relates to one of Bruce Miller’s patients, Louis F, who had a form of fronto-temporal dementia: Louis sang repeatedly but the semantic content, the meaning, of the song was lost to Louis – it was just a song and the words could be replaced with nonsense that rhymed and scanned. On p345 there is a paragraph… “Miller has written about ’empty speech’ with regard to patients with fronto-temporal dementia, and most of what Louis said was repetitive, fragmented and stereotyped. ‘Every utterance, I’ve heard before,’ his wife remarked.” This idea of stereotypical speech needs further exploration – I suspect that there is a spectrum of speech-acts (for lack of a better phrase) from deliberate conscious speech (e.g. when you are trying to communicate a particularly gnarly idea for the first time) to oft-repeated phrases (e.g. when you are in conventional social situations or when you are delivering a lesson for the umpteenth time) to singing (which is not communicative and, once a song is learnt, need not be very deliberative).

Sacks’ book was originally published in 2007 and then revised/expanded in 2008. A more recent book ‘You Are the Music’ may bring some of these ideas up to date but I haven’t read that yet.